Different manufacturers use different terminology, so there’s no single answer to your question. In particular, some of the Chinese manufacturers will use the term “rocker“ for what would more commonly be called “retractive” switches so you may just have to verify with the manufacturer how everything works.
Rocker Usually Means a Two Position Latching Switch with a defined on and off position
A rocker switch is usually pressed at the top to turn on and then it stays in that position until pressed again at the bottom to turn off. This is easier to see on US style switches, but I did find an image from Schneider where you can see that one of the switches in a dual gang is in the on position and the other is in the off position.
So if you can look at the switch and tell whether it’s on or off by the switch position, then it’s a rocker. (It “rocks“ from one position to the other.)
This is useful for dumb switches, but not useful for smart switches, because there are many different ways to turn a smart switch on. You might turn it on physically at the wall, you might turn it on with the voice assistant like Echo, You might turn it on with a time schedule, or you might turn it on with an automation like when someone arrives home.
That means that a traditional rocker switch would quite often be out of sync so that when you looked at the switch it might look like it was on but it might actually be off.
Momentary/Retractive Switches work more like a traditional button switch: you press it to change state, but then the switch immediately returns to its resting position, whether it is on or off
In contrast, a momentary switch is designed so that when you physically press it it does move, but it doesn’t hold that new position. Instead, it immediately returns to its resting position.
This means that you can’t tell just by looking at the switch whether it is on or off. But it also means it never gets out of sync. So most smart switches are momentary. These are also called retractive (because the switch retracts to its resting position once the finger is removed.)
This video is in French, but you can see the person physically touch the TKB zwave retractive switch at the top to turn it on and touch it at the bottom to turn it off again. Notice how the switch goes right back to the resting position once his hand is removed each time. So you can’t tell by looking at the switch whether it’s on or off.
The problem is if you just see a picture of the switch in one position, you can’t always tell whether it’s a rocker or retractive. It won’t necessarily be obvious from the design. So you need to either see a video of it in use or you need to ask the manufacturer if it’s not obvious from the product description.
Pulse switches only turn on while the switch is physically held down, like many electric potato chipper devices
A pulse switch is most typically a momentary switch which does not change the state of the device except while the switch is physically being held in position. So a retractive switch turns the light on when you press it, the switch returns to its resting position, but the light stays on until you press the switch again.
A pulse switch turns the device on when you press it, but is soon as you remove your finger the switch returns to its resting position and current is withdrawn from the device.
These are commonly used for motors as a safety feature. You see these on some garbage disposal switches, on potato chippers, on some blenders.
This could be used for a smart switch, although not typically a light. And in most cases anything which isn’t safe to be left with the power on probably isn’t safe to use with Home Automation. But it’s not impossible.
Again, just looking at a photograph may not tell you whether the switch is a pulse switch, a momentary switch, or a latching rocker switch. All three might look identical. It’s only when you see them in operation and you can tell whether the switch pops back to its resting position and whether the state change is maintained when it does, that you know which of the three it is.
(Notice some manufactures use the term “momentary” to mean pulse. That is, as soon as the finger is removed, the switch is off again. But that usually applies to dumb switches. For whatever reasons, Home Automation device manufacturers about 20 years ago started calling retractive switches momentary switches even though the device retains the state change when the hand is removed, so for smart switches, momentary usually means retractive. But for dumb switches it might mean either retractive or pulse.)
I hope that helped. The concept is pretty easy to understand but what applies to any given switch model can be hard to figure out, particularly for product descriptions which are translated from another language, without seeing it in operation.
